This invention relates to improvements in lifting rotors for helicopters and other rotary wing aircraft. Two persistent problems with prior art rotary wings which are overcome by this invention are mechanical complexity and poor flying qualities.
Conventional rotary wing aircraft are dynamically unstable in flight. Therefore if a conventional rotary wing aircraft experiences a flight disturbance, such as a gust of wind for example, the rotor will react in such a manner that the upsetting effect of the original disturbance is magnified. The usual result is a dynamic pitching or rolling oscillation of the aircraft which will increase in severity unless corrective action is taken by the pilot. This undesirable characteristic of conventional rotary wing aircraft makes them much more difficult to fly than fixed wing aircraft. The constant attention required from the pilot, particularly during hovering flight, makes conventional rotary wing aircraft virtually unsafe to fly at all under instrument flight conditions unless they are equipped with auxiliary stabilizing devices.
A number of such devices have been developed to counteract the instability of conventional rotary wing aircraft. These include gyro-stabilized electro-mechanical autopilots and direct-acting mechanical gyroscopic devices for example. These devices provide artificial pitch and roll damping which reduces the dynamic instability of the conventional rotary wing. However, electro-mechanical autopilots are expensive and complex while direct-acting mechanical gyroscopic devices are heavy and usually increase the aerodynamic drag of the rotary wing adversely affecting its flight performance. It is apparent, therefore, that it is desirable to have an inherently stable lifting rotor which eliminates the need for these stabilizing devices.
The general object of the present invention is to solve the stability problem of conventional rotary wing aircraft as well as certain other problems related thereto while providing a mechanically simple, aerodynamically clean rotary wing.